1. Field of the Invention
The present invention refers to a new acylating method of transforming primary or secondary organic amines into corresponding acyl compounds conveniently by using 1,3-dihydro-1,3-diacyl-1H-benzimidazole-2-one derivatives. Especially, this method showed good regioselectivity in case of diamino compounds where primary and secondary amino group coexist in the same molecule. Two amino groups of diamino compounds which experience different steric or chemical environment showed different reactivities toward this present acylating agent. So it is possible to transfer acyl groups selectively in these diamino system.
2. Description of the Related Art
Until now, N,N'-diacylimidazolone derivatives were presented in U.S. Pat. No. 3,775,333, 1973, as a bleaching activator, but no one has reported the derivatives as an useful acylating agent until the present invention.
The traditional methods for transforming organic amines into acyl compounds were by using acid halide or acid anhydride as acylating agents. However, there are shortcomings, an additional step is required to remove the hydrogen halide or carboxylic acid which is liberated after the reaction. In some cases, the reagent itself which was used to remove the hydrogen halide or carboxylic acid affected the acylated compound or caused difficulties in the purification of the final product.
Where two amines with different steric hindrance and reactivity coexist within one molecule, it is nearly impossible to achieve a selective acylation by using such an acylating agent. For instance, it is rarely possible to acylate a specific amine selectively by using hydrogen halide or acid anhydrides where aminobenzilamine or diamino compounds which have primary and secondary amino groups, or where amines that have structurally different reactivity or steric hindrane. hindrance.
Accordingly, many acylating agents has been reported as candidates of selective acylating agents in a large number of publications and patents. Representative examples are N-acylimidazole (Fieser & Fieser, Organic Reagents), 3-acyl-2-oxazolone (Tetrahedron Lett., 22, 1981, 1257-1258), 3-acythiazol-2-thione (Tetrahedron Lett., 21,1980, 841-844) and N,N-diacetylaniline (Tetrahedron Lett. 38, 1997, 3751-3754). However, the selectivity of the acylation reactions is limited to these acylating agents, and it is difficult to purify the products, and it is restricted to transfer only one amine.